SELACHOIDEI. 



327 



over the mouth, with a free cylindrical cirrhus on each side. 

 Teeth small, trilobed, in many series, occupying in both jaws a 

 transverse flat sub-quadrangular patch. The fourth and fifth 

 gill-openings are close together. 



The single species (aS'^. tigrinum) for which this genus has 

 been formed, is one of the commonest and handsomest sharks 

 of the Indian Ocean, Young individuals keep generally close 

 to the coasts, whilst the adult, which are from 10 to 15 feet 

 long, are not rarely met in the open ocean. The colour is a 

 brownish yellow, ornamented with black or brown transverse 

 bands, or with snuff-coloured rounded spots ; hence this shark 

 is frequently mentioned by the names oi " Zebra-Shark " or 

 " Tiger-Shark." 



Chiloscyllium. — The first dorsal fin above or behind the ven- 



Fig. 116. — Chiloscyllium trispeculare, froriT North-western Australia. , 



trals. Anal fin placed far behind the second dorsal, and very 



close to the caudal. Spiracle very 



distinct, below the eye. Nasal 



and buccal cavities confluent. 



Nasal valve folded, with a cirrhus. 



Teeth small, triangular, with or 



without lateral cusps. The two 



last gill-openings close together. 



" Dog-fishes," from the In- 

 dian Ocean, of small size. Four 

 species are known, of which 

 one, Ch. indicum, is one of the Fi 

 commonest shore-fishes on the 

 coasts of this region, extending from the southern extremity 

 of the African Continent to Japan. 



117. — Confluent nasal and buccal 

 cavities of the same fish. 



